International Journal of Enhanced Research in Science, Technology & Engineering
Automation of Mill Using PLC & Drives to Increase The Production, Energy Saving & Protection of Equipments
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International Journal of Enhanced Research in Science, Technology & Engineering
Sukhchain Singh1, Gurpreet Kaur Gill2
1Student, Guru Nanak Dev Engineering College, Ludhiana, India
2Asst. Professor, Dept. of Electrical Engg, GNDEC, Ludhiana, India
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International Journal of Enhanced Research in Science, Technology & Engineering
Page | 1
International Journal of Enhanced Research in Science, Technology & Engineering
Page | 1
International Journal of Enhanced Research in Science, Technology & Engineering
ABSTRACT
The aim of this thesis work is to increase the production, energy saving & protection of equipments in a mill using PLC automation & drives. The mill Bharatam Tmt Bars Pvt. Ltd., Mandi Gobindgarh is going towards the danger of shutdown because of less production. For this work, a case study is done in which primarily all data regarding the reasons of faults in the mill responsible for the unnecessary shutdown for the year 2013-14 has been collected. Then before automation production of the mill has been calculated. On the basis of data collected, responsible factors by which the production of mill has been affected are analyzed. According to this analysis, automation has been done by using PLC to increase the production and protection of equipments. To achieve the objective of energy savings, data of different motors which are consuming high energy during daily production process has been collected. Production and performance of different equipments or motors before and after automation has been calculated and compared. Also production of the mill after automation has been calculated. Production of mill can be increased twice approximately and after automation of mill, approximately 20% of energy is saved and about 21% loading is reduced. Payback period and energy savings have been calculated.
Keywords:Thermo Mechanical Treatment (TMT), Programmable Logic Controller (PLC), Automation, Drives.
1. INTRODUCTION
In this fast improving and ever demanding world, industrial growth is also picking up the pace. All large scale industries can easily achieve the target of high production from the demanding customers but for small scale industries it is very difficult to run according to high demands of costumers by keeping in the mind that the costs of energy is increasing day by day. So, small scale industries or mill management must have to achieve some goals which include:
1. To increase the production of mill.
2. To increase the energy savings by keep in the mind the costs of energy.
3. To protect the mill equipments from faults and unwanted shut downs and also to maintain the overall setup for proper operations and continuous production.
If management is unable to achieve these goals it will results to shut down soon. To prevent the shutdown, mills are needed to upgrade conventional system into automatic system because all above mentioned goals can be achieved easily by using automation.
PLC and Drive was discovered to fulfill the requirements of Automotive Manufacturing Industry in America. Back in 1838, first drive was designed by B.S. Lakobi in Russia. In 1870 this drive was widely used in industrial applications. The proposal of hard wired electronic relay systems replacement was issued by GM Hydramatic in 1968. A memory was fixed in drive to store the program, user instructions and functions like on & off control, sequence of timing, arithmetic counting and data handling. Today it can be seen that theses drives, PLC and automation equipments are used in almost every application.
· NEED OF AUTOMATIC CONTROL
1. Automatically controlled system can provide long time protection to the transformer, motors and other electric equipments comparatively at low cost using less power.
2. Overloading conditions can be judged and prevented by automated system (sensors, PLC & drives).
3. High cost differential relays and other electromechanical relays can be replaced with the use of PLC logic control system.
4. Every information concerned with working equipments can be controlled in control room by operator to build up better strategy to manage and control different conditions.
5. Less manpower required which reduces human errors.
6. Automatic system reduces operational cost, maintenance and energy consumption.
· WHAT IS AUTOMATION?
Automation is automatic operation of equipments such as machines, boilers, factory processes, heat ovens, stabilization of ships and steering, aircraft and other applications with reduced human efforts by using various control systems.
The benefit of using automation is that it saves energy, labour cost, material consumptions and also improve accuracy, process quality and precision. Before 1947, automation was not widely used. In 1930s feedback controllers were rapidly adopted by industry.
Automation achieved by various means including mechanical, pneumatic, hydraulic, electronic, electrical and computers were mostly in combination. Complicated systems, such as airplanes, ships and modern factories typically used all these combined techniques.
· ENERGY AUDITING: PRINCIPLE AND ITS OBJECTIVE
It is a technique which is used to establish the pattern of energy use, identify how and where the losses are occurring and at which areas wastage of energy is more and then suggest appropriate
economically engineering solutions to save the energy in the system.
Principle of energy audit is the study of a process or a system and to reduce the consumption of energy while improving or maintaining human health and considering safety as primary concern.
The objective of the energy audit is to determine & achieve the methods for optimum energy consumption and its utilization, throughout the organization to minimize energy costs/wastage without affecting production, quality and environmental effects.
2. STRUCTURE OF PROPOSED SYSTEM
A. Methodology used
To accomplish the objectives, following methodology canbe adopted:
1. Observed the overall production procedure of the mill and estimate the production at present conditions.
2. Collected the failure data of mill responsible for maximum shut down for year 2013-14.
3. On basis of data collected, factors affected the performance of the mill was analyzed.
4. On the basis of analysis, automation was done with the help of plc and drives, so as to reduce the faults and energy wastage of the equipments.
5. Production rate & performance of different equipments of the mill, before and after the automation was calculated & compared.
6. Payback period and energy saving was calculated.
B. Collected Data
1. Data of faults due transformer & motors
MotorsS no. / Name of faults / Shutdown period (in hrs)
1. / Phase-phase winding short circuit / 6
2. / Earth fault / 12
3. / Overloading (temp. Rise) / 36
4. / Supply fault / 6
5. / Miscellaneous faults / 2
6. / Bearing break / 4
Total shutdown hours in a year / 66
Table.1. Analysed factors causing shutdown due to motor faults
From the observation of mill, it is estimated that shutdown of mill during the process due to some faults has been the major reason behind the low production of mill and data of faults is:
Table.2. Analyzed factors causing shutdown due to transformer faults
TransformerS no. / Name of faults / Shutdown period (in hrs)
1. / Temp. Rise / 5
2. / Winding short circuit / 24
3. / Oil leakage / 3
Total shutdown hours in a year / 32
Table no. 1, 2 are showing the electrical faults of motors and transformer which are major cause of mill shutdown than other faults; hence electrical faults are taken up for analysis.
2.Data of Motors
Table.3. Rated data of motors
S no. / Motor Applications / HP / KW / RPM / Rated Curr. Ir (A) / Efficiency (%)1. / Coal tank output / 5 / 3.7 / 1140 / 7.5 / 89
2. / Conveyor / 7.5 / 5.6 / 960 / 11.25 / 90
3. / Shear / 20 / 15 / 1440 / 29.8 / 83
4. / Water pump / 30 / 22 / 1440 / 43.5 / 87
5. / Coal tank input / 40 / 30 / 1440 / 58.3 / 82
6. / TMT pump / 60 / 45 / 2800 / 87.5 / 82
7. / Blower & APCD / 75 / 56 / 1440 / 83.8 / 89.5
8. / Main motor 2 / 100 / 75 / 735 / 144.6 / 90.6
9. / Main motor 1 / 150 / 112 / 735 / 208.2 / 81
Table no. 3 is showing the rated data of motors which are playing major role to produce the total production of mill. Table is showing application of motors where they are working along with their HP, KW RPM, Rated current and Efficiency.
C. Automation for Electrical Faults
1. Transformer automation by PLC
Automation of transformer faults by using PLC is explained below:
· Reduction of temp. Rise by control of cooling fans.
When the flux of primary winding and secondary winding links with each other then heat is produced due to losses in the core. This heat is transferred to the winding of transformer and then to the oil of transformer. Transformer oil is provided in transformer for cooling and better insulation purpose. For cooling of transformer walls heat sinks are used. Heat is transferred to heat sink & no. of fans is connected in parallel to provide cooling to transformer walls. There is necessity to control them according to need, because temperature in night time and day time in summer session or in winter session are different. For automation purpose different type of heat sensors like Thermistor, Thermocouple, Optical sensors are used based on requirements. Output of sensor can be used as input of PLC and fans will operate according to output of PLC.
Fig.1. Transformer cooling fans
· PLC Control of Cooling Fans
PLC programming is done with Zelio Soft 2 software.
1. Input Z1 is the output of temperature sensor, CC1 is up counter which will continuously feed counted data in to the comparator V1. In any case temp. 20* C<Z1<60* C then Q1 output will energies, which will on selected fans.
2. In case temp. 60* C<Z1<85* C then Q2 will energies which will on more selected fans.
3. In case temperature 85* C<Z1<95* C then Q4 will energize which will turn on all fans
and an alarm.
4. In case temp. Is more then 95* C then Q4 will be energized and produce a trip signal to provide a safety for transformer in overheating conditions.
5. RC1 is reset coil of counter CC1 and Z2 is reset input.
Fig.2. PLC programming of cooling fans
· Oil Leakage Control using Pressure Sensor
It is very important to find out any fault occurring in transformer due to leakage of oil. Basically it is done by measuring pressure inside the transformer. Measurement of pressure inside transformer is the basic principle for finding oil leakage in transformer. Using pressure sensor pressure inside the transformer can be easily measured. For automation purposes output of pressure sensor is Z1 which is input to counter CC1. If the value of pressure is equal to set value 5 in comparator then alarm Q1 will get on. If value of pressure is further increasing and reaches equal or greater than 7 then trip signal Q2 will be produced.
Fig.3. PLC programming of Pressure Sensor
2. Protection of motors using drives
In a mill motoring load is approximately 75-85 % of load is actually the motoring load out of the total mill load. Due to continuous operation motors has to run all the working hours without any rest and it is also necessary to run the motors without any fault during all working hours even when they are loaded or not loaded, which is not possible and also there is loss of energy thus their protection is also most important.
Table 4. Rated data of motors
S n / Applications / HP / KW / RPM / Ir (A) / Effi.1. / Coal tank o/p / 5 / 3.7 / 1140 / 7.5 / 89
2. / Conveyor / 7.5 / 5.6 / 960 / 11.25 / 90
3. / Shear / 20 / 15 / 1440 / 29.8 / 83
4. / Water pump / 30 / 22 / 1440 / 43.5 / 87
5. / Coal tank i/p / 40 / 30 / 1440 / 58.3 / 82
6. / TMT pump / 60 / 45 / 2800 / 87.5 / 82
7. / Blower & APCD / 75 / 56 / 1440 / 83.8 / 89.5
8. / Main motor 2 / 100 / 75 / 735 / 144.6 / 90.6
9. / Main motor 1 / 150 / 112 / 735 / 208.2 / 81
These motors play most important role during the operational hours to run continuously on load and no load conditions. No load conditions increases their maintenance, causes energy losses and faults. So there is need to protect them from faults and reduce energy losses by using drives.
A. Loading & energy consumption calculations of motors with-out using drives
Loading & energy consumption calculations of motors without using drives are shown below:
1. For 5 HP motor
Rated KW = 3.7
Rpm = 1440
Efficiency = 89%
Rated current (Ir) = 7.5A
Input current (Ii) = 5A
% loading = (Ii / Ir) x 100 = (5/7.5) x 100 = 66%
Actual loading = (kw x % loading / 100) = (3.7 x 66 / 100) = 2.44
Energy consumption / day = (actual loading / efficiency x 100 x total working hrs in a day)
= (2.44 / 89) x 100 x 8 = 21.93 KWH
Energy consumption / year = energy consu. / day x no. of working hrs in a year
= 21.93 x 310
= 6799 KWH
Similarly related data calculated for all motors
Table 5. Data calculated for all motors without using drives
S no. / HP / KW / Load current Ii (A) / % loading / Energy consumption / year(KWH)
1. / 5 / 3.7 / 5 / 66 / 6799
2. / 7.5 / 5.5 / 7.8 / 69 / 10468.7
3. / 20 / 15 / 20.8 / 70 / 31373.5
4. / 30 / 22 / 28.3 / 65 / 40763.2
5. / 40 / 30 / 45.5 / 78 / 70773
6. / 60 / 45 / 61.25 / 70 / 95268.3
7. / 75 / 56 / 60.3 / 72 / 111724.7
8 / 100 / 75 / 108.5 / 75 / 153977
9. / 150 / 112 / 150.7 / 72 / 246884
Total / 768031.4
B. Production of mill before automation